Browsing by Author "Narvadeshwar Kumar"

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Phytochemical Mediated Synthesis of CuO Nanoparticles and Its Evaluation for Electrocatalytic Oxygen Reduction Reaction Activity
(John Wiley and Sons Inc, 2025) Shyam Raj Yadav; Jai Prakash; Manisha Kumari; Kumari Rinki; Piyush Kumar Sonkar; Narvadeshwar Kumar
A successful preparation of copper oxide nanoparticles (CuO NPs) by using aqueous leaves extract (PE) of plant Combretum roxburghii Spreng. (C. roxburghii Spreng.) and its application towards oxygen reduction reaction (ORR) are reported here. Aqueous PE was added portion wise into an aqueous stirred solution of CuSO4.5H2O at ambient temperature to furnish CuO NPs particles. These prepared CuO NPs were characterized by inductively coupled plasma atomic emission spectroscopy (ICP-AES), Fourier transforms infrared spectroscopy (FTIR), ultraviolet-visible (UV–vis) spectroscopy, X‑ray diffraction (XRD), scanning electron microscope (SEM), high resolution-transmission electron microscopy (HR-TEM), and thermogravimetric analysis (TGA). ICP-AES and SEM mapping established the existence of Cu in prepared NPs. The size of prepared CuO NPs had been found in the range of 2.06 to 6.20 nm with distorted spherical shape by HR-TEM. The average size of the CuO NPs determined by HR-TEM was ∼4.23 nm. Solid residue obtained after evaporating water from PE is designated as PE (solid). Both PE (solid) and CuO NPs were layered on glassy carbon (GC) electrode to form modified electrodes, designated as GC/PE and GC/CuO NPs, respectively. These GC/PE and GC/CuO NPs electrodes were subjected to cyclic voltammetry (CV) characterizations. It was found that GC/CuO NPs displays decent electrocatalytic efficiency for ORR. GC/CuO NPs also exhibits outstanding working constancy (up to 1000 CV cycles). © 2025 Wiley-VCH GmbH.
Synthesis and Characterization of Plant Derived Copper Oxide Nanoparticles and Their Application towards Oxygen Reduction Reaction
(John Wiley and Sons Inc, 2022) Jai Prakash; Himanshu Shekhar; Shyam R. Yadav; Piyush K. Sonkar; Narvadeshwar Kumar
In this work copper oxide nanoparticles (CuONPs) are prepared from precursor CuSO4.5H2O using plant leaves extract (PEE) of Eranthemum pulchellum(E. pulchellum).The synthesized CuONPs are characterized by ultraviolet visible (UV-vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). CuONPs are distorted spherical in shape, with the sizes ranging from 5 to 17 nm. PEE and CuONPs are coated on glassy carbon (GC) electrode and abbreviated as GC/PEE and GC/CuONPs, respectively. The modified electrodes GC/PEE and GC/CuONPs are characterized with cyclic voltammetry (CV) techniques. The modified electrode GC/CuONPs exhibits good electrocatalytic activity for oxygen reduction reaction (ORR). GC/CuONPs also shows excellent operational stability up to 1000 CV cycles. © 2022 Wiley-VCH GmbH.
Teak wood-derived mesoporous carbon and its composite with molybdenum sulphide for electrochemical oxygen reduction
(Springer, 2025) Narvadeshwar Kumar; Smita Singh; Shubham Joshi; Mamta Yadav; Devesh Kumar Singh; Piyush Kumar Sonkar; Vellaichamy Ganesan
Abstract: In this work, a mesoporous carbon (MPC) material was prepared from teak wood (Tectonagrandis) sawdust. Further, a composite of molybdenum sulphide (MoS2) and MPC (MPC–MoS2) was prepared. The synthesised materials were characterized by different spectroscopic and microscopic techniques. Fourier transforms infrared spectrum of MPC–MoS2 indicates a weak interaction between MPC and MoS2. Raman studies revealed a slight decrease in the graphitization (compared to MPC) of the MPC–MoS2 due to the integration of MoS2 on MPC. X-ray diffraction patterns of MPC–MoS2 demonstrates the hybrid nature of the composite. Scanning electron microscopy images expose the morphology of the MPC–MoS2 as a rough and granular surface with small-sized flake-like appearances due to the presence of MoS2 on the surface of MPC. Hydrodynamic voltammetry studies on the MPC–MoS2 material disclose an efficient oxygen reduction activity. Based on the rotating ring disc electrode studies, a direct four-electron reduction of oxygen was established. Therefore, MPC–MoS2 could be employed as an efficient low-cost material to replace the high-cost Pt-based oxygen reduction catalysts which are currently being used in commercial fuel cells. © Indian Academy of Sciences 2025.